ActiveRecord Analyze
This gem adds an analyze method to Active Record query objects. It executes EXPLAIN ANALYZE on a query SQL.
You can check out this blog post for more info on how to debug and fix slow queries in Rails apps.
Installation
In your Gemfile:
gem 'activerecord-analyze'Options
The analyze method supports the following EXPLAIN query options (PostgreSQL docs reference):
VERBOSE [ boolean ]
COSTS [ boolean ]
SETTINGS [ boolean ]
BUFFERS [ boolean ]
TIMING [ boolean ]
SUMMARY [ boolean ]
FORMAT { TEXT | XML | JSON | YAML }
You can execute it like that:
User.all.analyze(
format: :json,
verbose: true,
costs: true,
settings: true,
buffers: true,
timing: true,
summary: true
)
# EXPLAIN (FORMAT JSON, ANALYZE, VERBOSE, COSTS, SETTINGS, BUFFERS, TIMING, SUMMARY)
# SELECT "users".* FROM "users"
# [
# {
# "Plan": {
# "Node Type": "Seq Scan",
# "Parallel Aware": false,
# "Relation Name": "users",
# "Schema": "public",
# "Alias": "users",
# "Startup Cost": 0.00,
# "Total Cost": 11.56,
# "Plan Rows": 520,
# "Plan Width": 127,
# "Actual Startup Time": 0.006,
# "Actual Total Time": 0.007,
# "Actual Rows": 2,
# "Actual Loops": 1,
# "Output": ["id", "team_id", "email"],
# "Shared Hit Blocks": 1,
# "Shared Read Blocks": 0,
# "Shared Dirtied Blocks": 0,
# "Shared Written Blocks": 0,
# "Local Hit Blocks": 0,
# "Local Read Blocks": 0,
# "Local Dirtied Blocks": 0,
# "Local Written Blocks": 0,
# "Temp Read Blocks": 0,
# "Temp Written Blocks": 0,
# "I/O Read Time": 0.000,
# "I/O Write Time": 0.000
# },
# "Settings": {
# "cpu_index_tuple_cost": "0.001",
# "cpu_operator_cost": "0.0005",
# "cpu_tuple_cost": "0.003",
# "effective_cache_size": "10800000kB",
# "max_parallel_workers_per_gather": "1",
# "random_page_cost": "2",
# "work_mem": "100MB"
# },
# "Planning Time": 0.033,
# "Triggers": [
# ],
# "Execution Time": 0.018
# }
# ]Optionally you can disable running the ANALYZE query and only generate the plan:
User.all.analyze(analyze: false)
# EXPLAIN ANALYZE for: SELECT "users".* FROM "users"
# QUERY PLAN
# ----------------------------------------------------------
# Seq Scan on users (cost=0.00..15.20 rows=520 width=127)Disclaimer
It is a bit experimental and can break with new Rails release.